Hey fellas. There is a thread in the 'How to get your ex back' section with the long version of what happened and the aftermath, but the short version is as follows: We dated for 2 years and live together for 6 months. Just before our 2 year anniversary I had a one night stand while on a business trip. Somehow she found out and I came home to find all her stuff gone, with only her phone left behind (because we were on a couple's plan I guess). I never even had a chance to explain. I don't know where she is living, I don't know her new phone number and she has blocked me on email and Facebook. I tried calling her at work but the calls all go through a switchboard and I'm told she "unavailable" and not given a chance to leave a message. And because she works in a hospital where the ER is behind doors and not just anyone can just walk in I can't just drop in to see her. In short I have no way to see or contact her.
Last night after a few drinks at the bar my buddy really wasn't feeling well and I jumped at the chance to take him to the ER knowing she would be there. After we were admitted and he was in a room I was waiting to bump into her. However before that happened I heard 2 nurses outside by the nursing station gushing about the new security guard. I was only half paying attention until one of them said that she switched shifts with *girlfriends name* on New Years Eve because the security guard had asked her on a date. So now I'm reeling. We just broke up, I know she still loves me and already she is going out with someones else. I listened to more of the nurses conversation and apparently security guard is new and just got out of the army. Which is a huge thing because my girlfriend was also in the army for 10 years. When the nurse came in to attend to my buddy I asked her if *girlfriends name* was working, but she just gave me the stinkeye and walked out of the room. After I heard my girlfriend's voice down the hallway so I went out to talk with her. She tried to run past me saying she had a patient to deal with but I just stood there and kept talking. She wouldn't listen and kept cutting me off when I tried to explain and confront her about her date (which she did admit to) she said she would get a restraining order if I ever contacted her again. Security ended up coming and escorting me out. I was told my buddy was drunk and nothing more and would be kicked out when he sobered up. I was told if I come back and bother my girlfriend the police will be called, and I was escorted out because I had interfered with her trying to help a patient (whatever).
I can't believe any of this. I am reeling that she is moving on so quickly. I just want to explain and tell her I'm sorry. What PUA techniques or other things can I do to get her back? Please help guys. I know this seems like oneitits but I wanted to marry this girl one day and don't want to lose her over one stupid mistake.